This invention relates to a method of compressing digital image data and a device thereof for a digital image recording device, and more particularly to a method of compressing digital image data and a device thereof capable of coding the digital image data within predetermined constant rate data.
Generally, there is disclosed a device for recording a color still image converted into digital data on a recording media such as a magnetic tape or an integrated circuit (IC) card.
The digital image data is formed properly as a plurality of blocks for performing a conversion-coding such as a discrete cosine transform (DCT) in such digital image recording device. The blocks is produced by dividing an original image by a unit of 8.times.8 pixels or 16.times.16 pixels. A conversion factors are produced by applying the DCT conversion coding to the blocks. The conversion factors are Huffman-coded and variable-length-coded through a proper quantization. A union group JPEG (Joint Photographic Experts Group) of the CCITT (Consultative Committee on International Telegraphy and Telephony) and the ISO (International Standard Organization) recommended the method of compressing and coding the digital image data by the above described steps on Feb. 1990.
The conventional method described as above has a problem that a quantity of compressed data is changed according to a complexity of an input digital image data. Especially, it is not desirable that the quantity of digital image data is changed in a still video camera for compressing and recording digital data on a record media such as an IC card because the number of scenes of a digital image recorded on the IC card may be changed according to a complexity of the input image contents.
Therefore, a user experiences an inconvenience since the number of scenes to be recorded on one IC card made of static random access memory (SRAM) is not predictable.